SAN DIEGO -- One of the finest pitchers of his generation, Felix Hernandez will turn 31 years old in April. But he already began looking old last season.

In probably his worst season in a decade, the 2010 Cy Young winner and six-time All-Star went 11-8 with a 3.82 ERA. His velocity dropped to around 90 mph, he struggled with his control and his strikeout-to-walk ratio fell to the lowest of his career at 1.88. As rough as all that was, he says the worst part was being on the disabled list for nearly two months with an injured right calf. "I'm not used to being on the DL," he said.

Things went so poorly for King Felix that at the end of the season, Seattle Mariners manager Scott Servais said Hernandez would have to make adjustments during the winter to "come into spring training in a little better shape and with more urgency."

Hernandez did so, working out extensively during the offseason. "It was really good," he said. "I worked out more this offseason than ever before. I did it to get back where I used to be three years ago."

He also pitched briefly in the Venezuelan Winter League, partly in preparation for the World Baseball Classic. Hernandez had pitched in the 2009 WBC, but he skipped the 2013 tournament while finalizing a seven-year, $175 million contract with the Mariners. He made certain to return to the WBC this year.

"He’s one of the best pitchers we’ve had in Venezuela -- his career has been phenomenal," Venezuela general manager Carlos Guillen said. "He prepared himself for this tournament, preparing from November. He wanted to be 100 percent for this tournament."

Felix Hernandez started preparing for the WBC in November after having his worst MLB season in 2016. Alex Gallardo/AP Photo

Hernandez struggled in his first WBC start, but he looked close to his old form against the United States on Wednesday night when he threw five scoreless innings, allowing just three singles while striking out three. He also didn’t walk anyone.

With Venezuela going on to lose that game, as well as Thursday’s against the Dominican Republic, it might be Hernandez's last game in this WBC. If so, he will return to Mariners spring training and continue working to improve.

After watching Hernandez pitch Wednesday night on TV, Servais told reporters in Arizona that he was impressed with his performance, and that he used his secondary pitches differently, as the coaching staff has recommended.

"He tried them all last night and had success with all of them," Servais told the reporters. "That’s great. That’s what you want to happen when you are discussing different things. But he had great feel for all of them last night. So it’s going to be easier when you have that many weapons to go to."

One of the best and most popular players in Mariners history -- Seattle fans fill the King’s Court down the left-field line whenever he pitches -- Hernandez made his major league debut at just 19 years old. After he pitched eight scoreless innings to win his first game, a Seattle columnist said Hernandez would be the next Bob Gibson, Roger Clemens or Pedro Martinez. He’s certainly been impressive. In addition to winning the 2010 Cy Young, the King has finished second twice, received votes three other seasons and also pitched the first perfect game by a Mariner in 2012.

Hernandez also has thrown a lot of pitches, averaging 228 innings a season from 2009 to 2015. That wear on his arm is one possible reason for the decline in his velocity, which once was around 96 mph. Asked whether he thinks his velocity will pick up thanks to his offseason training, Hernandez replied, "I don't know. I think it takes time."

As great as his career has been, though, there is one glaring omission on his resume. Hernandez has never pitched in the postseason. The Mariners have gone the longest of any current team without reaching the playoffs (15 seasons). They came somewhat close last season, finishing in second place in the American League West, nine games behind the first-place Rangers and three games behind the wild-card Baltimore Orioles and Toronto Blue Jays. They might have come closer -- or even made the postseason -- had Hernandez been in his usual form.

Some predict Seattle will reach the postseason this year, though the Mariners’ chances probably depend on King Felix returning to the throne from which he ruled many seasons before his struggles last year. Hernandez says they can do it.

"I think we're good. We're different now," Hernandez said. "We're going to be more energetic, and it will be more fun. We've got more hunger, and we want to win."